The present invention relates to an aluminum based alloy having excellent mechanical properties and suitable for applications in temperature ranges between −420° F. to 573° F.
Aluminum alloys have been used in aerospace and space applications owing to their good combination of strength, ductility and density. Aluminum alloys are, however, limited in their use at temperatures above 300° F. as most aluminum alloys at these elevated temperatures lose their strength due to rapid coarsening of strengthening precipitates.
There has been considerable effort in the prior art to improve the high temperature strength of aluminum alloys up to and exceeding 500° F. Prior attempts to improve the high temperature mechanical properties of aluminum alloys have included (a) aluminum-iron and aluminum-chromium based alloys that contain incoherent dispersoids and (b) mechanically alloyed pure aluminum and aluminum alloys strengthened by incoherent oxide particles. The strength of the aluminum alloys provided from approach (a) above tended to degrade at high temperatures due to coarsening of incoherent dispersoids. In addition, these aluminum alloys exhibited lower ductility and fracture toughness due to large volume fraction of incoherent particles. Accordingly, these alloy systems have not found widespread applications particularly with respect to high temperature environments. Some of the alloys considered for approach (b) included commercially pure aluminum, Al—Mg and Al—Ti produced using mechanical alloying processes. While these aluminum alloys showed promising strengths at high temperature, these alloys did not find widespread applications in high temperature environments possibly due to lower ductility and fracture toughness. See also U.S. Pat. No. 3,816,080. U.S. Pat. No. 6,248,453 discloses Al—Sc based alloys which contain high volume fractions of strengthening coherent dispersoids. While these alloys are useful at high temperatures, we would prefer a material with higher ductility and fracture toughness. Furthermore, the problem vis-à-vis low ductility and fracture toughness will be increased at cryogenic temperatures.
None of the prior approaches provides an aluminum alloy having excellent mechanical properties in the temperature range of −420° F. and 573° F.
Accordingly, it is the principle object of the present invention to provide an aluminum alloy having excellent mechanical properties and suitable for applications in temperature ranges of −420° F. to 573° F.